Solving a word problem with three Unknown linear

Question

Rita, David and Allie have a total of $84 in their wallet. Allie has two times what Rita has David has eight dollars less than Rita. How much does each have

Answer 1

R+D+A= 84

A= 2R

D=R-8

R+R-8+2R= 84

4R=92

R=23

A=2R=2*23=46

D=R-8=23-8=15

Answer 2

R + D + A = 84

R = R

A = 2R

D = R - 8

Can you sobstitute in first equation, solve for R and answer?